with a fluctuation-dissipation-theorem (FDT) expression [1]} for the static structure factor,
\(S^{(\lambda )}(q, T) = -\frac{1}{\pi n}\int _0^{+\infty }d\omega ~\coth {(\beta \omega /2)}\Im m \chi ^{(\lambda )}_{\rho \rho }(q,\omega , T)~.\) 
